Endovascular stent graft

ABSTRACT

An endovascular stent graft assembly ( 10 ) for use with abdominal aorta aneurysms ( 70 ) and having a main stent graft body ( 12 ) and a separate attachment graft tube ( 14 ) that extends proximally therefrom having the proximal attachment stent ( 50 ) thereon for infrarenal attachment of the assembly ( 10 ) to the aorta ( 74 ). A distal end portion ( 44 ) of the attachment graft tube ( 14 ) underlies the proximal end portion ( 30 ) of the main stent graft body ( 12 ) and presses outwardly there against forming a a friction fit, at an overlapping region ( 64 ). The main stent graft body ( 12 ) has an ipsilateral leg ( 22 ) and a contralateral stump ( 24 ) at the bifurcation ( 26 ); and prior to deployment of the attachment graft tube ( 14 ), the main stent graft body is pulled against the vessel bifurcation ( 72 ). After deployment of the attachment graft tube ( 14 ), the contralateral leg ( 16 ) is deployed at the contralateral stump to complete the stent graft assembly ( 10 ). Preferably, an additional intragraft stent graft tube ( 18 ) is deployed to underlie and press outwardly and support the overlapping region ( 64 ) of the attachment graft tube and the main stent graft body.

RELATED APPLICATION INFORMATION

[0001] This application claims priority from U.S. ProvisionalApplication Serial No. 60/189,114 filed Mar. 14, 2000 and ProvisionalApplication Serial No. 60/202,468 filed May 8, 2000.

TECHNICAL FIELD

[0002] The present invention relates to medical devices and moreparticularly to endovascular devices.

BACKGROUND OF THE INVENTION

[0003] In recent years treatment of aneurysms has included the use ofstent grafts that are emplaced within the vascular networks and thatinclude one or more stents affixed to graft material. The stent graftsare secured at a treatment site by endovascular insertion utilizingintroducers and catheters, whereafter they are enlarged radially andremain in place by self-attachment to the vessel wall. In particular,stent grafts are known for use in treating descending thoracic andabdominal aortic aneurysms where the stent graft at one end defines asingle lumen for placement within the aorta and at the other end isbifurcated to define two lumens, for extending into the branch arteries.

[0004] One example of such a stent graft is disclosed in PCT PublicationNo. WO 98/53761 in which the stent graft includes a sleeve or tube ofbiocompatible graft material such as Dacron™ polyester fabric (trademarkof E. I. DuPont de Nemours and Co.) or polytetrafluoroethylene defininga lumen, and further includes several stents secured therealong, withthe stent graft spanning the aneurysm extending along the aortaproximally from the two iliac arteries; the reference also discloses themanner of deploying the stent graft in the patient utilizing anintroducer assembly. The graft material-covered portion of thesingle-lumen proximal end of the stent graft bears against the wall ofthe aorta above the aneurysm to seal the aneurysm at a location that isspaced distally of the entrances to the renal arteries. Thin wire strutsof a proximal stent extension traverse the renal artery entranceswithout occluding them, since no graft material is utilized along theproximal stent while securing the stent graft in position within theaorta when the stent self-expands. An extension is affixed to one of thelegs of the stent graft to extend along a respective iliac artery and,optionally, extensions may be affixed to both legs. Another known stentgraft is the Zenith AAA™ stent graft sold by William A. Cook AustraliaPty., Brisbane, Australia.

[0005] In prior art stent grafts, graft fixation was achieved byfixation at the top or proximal end by barbs or by a stent portion thatis uncovered by graft material and could be incorporated into the vesselwall. Distal end fixation was attained by friction within the branch oriliac arteries. The stents of the prior art stent grafts tended to beflexible and relatively soft. The proximal main tube graft was of astandardized length, and that length tended to be significantly shorterthan the aneurysms themselves, while the full length was bridged andachieved by smaller diameter extensions or legs.

[0006] With the prior art stent grafts, certain late complications werecommon: due to the above-mentioned configuration there was a certaininstability leading to kinking, obstruction of the lumen and/ordisintegration leading to possible graft explantation, wherein the stentgraft undesirably moved out of its intended position mostly due tolarger displacement forces within the smaller diameter stent graftportions; material fatigue also occurred, leading to endoleak whereinblood flow continued into the aneurysm.

SUMMARY OF THE PRESENT INVENTION

[0007] The foregoing problems are solved and a technical advance isachieved in the stent graft of the present invention. The stent graftassembly of the present invention includes a main stent graft device orbody with an integral ipsilateral leg and a contralateral stump thattogether define a bifurcation at the distal end, includes acontralateral extension, and further includes an attachment graft tube.The main stent graft body and the attachment tube at its proximal end,will together span the whole aneurysm, but the main stent graft bodyitself is selected to have a length that is less than the span of theaneurysm, measured proximally from the bifurcation of its ipsilaterallimb and the contralateral stump. The proximal end of the main stentgraft body is adapted to remain unattached to the vessel wall, unlikeconventional stent grafts, but the attachment tube proximal end includesan attachment stent for vessel wall attachment at the aneurysm proximalneck, with the attachment tube fully sealing relative to the aorta whilepermitting free flow to the renal arteries. Furthermore, in contrast tothe prior systems which started positioning at the top, proximally atthe renal arteries, the main graft assembly is built starting from belowat the distal bifurcation first and extending then from distal toproximal to the renal orifices at the aneurysm's proximal neck.

[0008] After partial deployment wherein the contralateral stump isreleased from the delivery system sheath, the main stent graft bodybifurcation is seated against the aortic vessel wall at the iliacarteries bifurcation, prior to deployment of the ipsilateral leg fromthe delivery system sheath. The second or attachment graft tube ofselected length then is brought up contralaterally through the mainstent graft body. The attachment tube is then deployed such that adistal portion of substantial length remains within the proximal end ofthe main stent graft body to define an overlap region, and an attachmentstent extending from the proximal end of the attachment tube is thendeployed to attach to the vessel wall at the proximal neck of theaneurysm at the renal arteries. The overlap region may be as little as 2mm to 5 mm in length but is preferably at least about 20 mm and there isa friction fit between the attachment graft tube distal portion and themain stent graft body proximal portion upon full deployment (expansion)of the stents of the attachment tube. The contralateral limb isthereafter moved into position and affixed to the contralateral stump.Preferably, both the attachment graft tube and the contralateral limbare delivered in a second double-sheath delivery system, through thecontralateral artery. Such an overlapping double tube result at theproximal end of the main stent graft body is stronger, and the positionof the stent graft assembly after full deployment is more stable againstexplantation.

[0009] Optionally, a third or intragraft tube is placeable into the mainstent graft body to underlie and extend in both directions beyond theoverlapping region between the main stent graft device and theattachment graft tube. The third graft tube would expand to define afriction fit within both the attachment graft tube and the main stentgraft body and have a length greater than the overlap region, thusstrengthening the friction fit between the attachment graft tube and themain stent graft body. Such third graft tube would be utilized shouldconfiguration changes of the aneurysm, and the subsequent increase inthe distance between the renal arteries and the bifurcation, tend topull the attachment graft tube partially from the main stent graft bodyand decrease the overlap region therebetween; such intragraft tube canbe easily placed during a subsequent procedure.

[0010] The present invention is also directed to a first graft member(corresponding to the attachment tube discussed hereinabove) that is tobe used in conjunction with at least one other graft member (the maingraft tube), and that includes an attachment region having an attachmentstent for attachment to a vessel wall, and a distal portion defininganother attachment region for attachment to the at least one other graftmember.

[0011] The present invention includes method aspects: a method ofplacing an endovascular stent graft in a vessel at a bifurcation thereofwhere branch vessels join the vessel, for treating an aneurysm thereat,comprising the steps of placing a bifurcated main stent graft body inthe aneurysm unattached to a wall of the vessel with a first leg portionin a first branch vessel; urging a bifurcation of the main stent graftbody into a seated position against the bifurcation of the vessel tomove a second leg portion in a second branch vessel; and securing thestent graft to the vessel wall.

[0012] In an additional aspect, the present invention includes adelivery system for endovascular devices, comprising a first sheathhaving a distal end and a proximal end and containing at least a firstexpandable device at a proximal end; a second sheath movable within thefirst sheath and having a respective distal end and a respectiveproximal end, the respective proximal end concluding distally of thefirst expandable device and containing a second expandable device; afirst pusher associated with the first expandable device extendingthereto within the first and second sheathes from a first proximalcontrol pusher end exposed at the distal ends of the first and secondsheathes; and a second pusher associated with the second expandabledevice extending thereto within the first and second sheathes from asecond distal control pusher end exposed at the distal ends of the firstand second sheathes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] An embodiment of the present invention will now be described byway of example with reference to the accompanying drawings, in which:

[0014]FIG. 1 illustrates the main stent graft device, having a mainbody, an ipsilateral leg and a contralateral stump;

[0015]FIG. 2 illustrates an attachment tube of the present invention,with a proximal end exposed beyond the graft material and whose lengthcan vary depending upon the length of the aneurysm;

[0016]FIG. 3 shows a contralateral leg for affixing to the contralateralstump, and having a flared distal end;

[0017]FIG. 4 illustrates an additional intragraft tube for within thelumen of the main stent graft body and the attachment tube for spanningand supporting the overlapping region therebetween;

[0018] FIGS. 5 to 7 show the sequence of steps in the delivery of thestent graft arrangement of the present invention, in which FIG. 5 showsthe main stent graft device being positioned and partially deployed inthe aneurysm and seated onto the vessel wall bifurcation; FIG. 6illustrates the introduction the second double-sheath delivery systeminto the main stent graft body; and FIG. 7 shows the deployment of theattachment tube and contralateral extension;

[0019]FIG. 8 shows a side view of an aneurysm having a representativePrior Art stent graft disposed therein;

[0020]FIG. 9 shows a side view of an aneurysm having a stent graft ofthe present invention disposed therein;

[0021]FIG. 10 illustrates the deployment of the intragraft tube withinthe stent graft, especially useful upon lengthening of the aneurysmduring shrinkage thereof;

[0022]FIGS. 11 and 12 show the delivery system, with FIG. 12 showing thetrigger wire controls included in the main body delivery system of FIG.11;

[0023]FIG. 13 illustrates the second double-sheath delivery systemcontaining the attachment tube and the contralateral leg and theirrespective pushers;

[0024]FIG. 14 shows another version of the second double-sheath deliverysystem in which the inflation balloon follows the attachment tube in thesystem;

[0025] FIGS. 15 to 18 depict the sequential deployment of the main stentgraft body and the attachment tube;

[0026]FIG. 19 is an enlarged view showing retention of the attachmentstent prior to deployment;

[0027]FIG. 20 shows enlargements of the trigger wire containmentarrangement for the attachment stent of the attachment tube and for thedistal end portion of the main body; and

[0028]FIG. 21 is an enlarged view of the distal end portion of the mainstent graft body illustrating maintaining the contralateral stump in aclosed condition during placement of the main stent graft body.

DETAILED DESCRIPTION

[0029] The stent graft assembly of the present invention includes a mainstent graft body or device 12, a second graft body or attachment tube14, and a contralateral limb extension graft 16, as seen in FIGS. 1 to 3in their fully expanded state, if unconstrained within a vessel ordelivery catheter. FIG. 4 shows an optional but preferred additional,intragraft tube graft body 18. Main stent graft body 12 includes aprimary graft section 20, an ipsilateral leg 22 and a contralateral limbor stump 24. Primary graft section 20 is disposed within the aneurysmand extends from the bifurcation 26 to a proximal end 28 of proximal endportion 30, and has a lumen with a relatively constant diameter D thatapproximates the diameter of a healthy section of the aorta, generallyabout 26 mm. Ipsilateral leg 22 is associated with the ipsilateral iliacartery and extends to a distal end or cuff 32 that is flared.Contralateral stump 24 is associated with the contralateral iliac arteryand coextends a short distance from bifurcation 26 to a distal end 34;preferably, it is spaced from ipsilateral leg 22 a distinct small gap 36therefrom for the length of the contralateral stump.

[0030] Main stent graft body 12, attachment tube 14, contralateral limb16 and intragraft tube 18 all comprise graft material 38 and a pluralityof self-expanding stents 40 that are secured to and along the graftmaterial either along the outer surface or inner surface of the graftmaterial such as by sutures. At cuff 32 of ipsilateral limb 22 of mainstent graft body 12, a stent is secured to the inner surface of thegraft material while the stent along the proximal end portion 30 may besecured to the outer surface. Along the proximal and distal end portions42, 44 of the graft material of attachment tube 14, the respectivestents adjacent to proximal and distal ends 46, 48 are secured to theinner surface. An attachment stent 50 is secured to the proximal end 46of attachment tube 14 containing pairs of struts 52 shown joined at ends54 that are adapted such as with barbs to lock to the vessel wall of theaorta, and being so fabricated as to be spring biased for the ends 54 totend to diverge and expand laterally to press against the vessel wallupon release at deployment. Proximal and distal end portions 56, 58 ofcontralateral limb 16 include stents secured along the inner surface ofthe stent graft material, with distal end portion preferably being acuff similar to cuff 30 of ipsilateral limb 22. Regarding intragrafttube 18, proximal and distal end portions 60, 62 include stents that aresecured along the inner surface of the graft material, while one or two(as shown) or more stents 40 may be secured to the outer surface of theintermediate region, or may be secured along the inner surface, ifdesired.

[0031] Preferably, the main stent graft device 12 would have a primarygraft section 20 with a proximal lumen about 24 mm in diameter andextending about 50 mm in length to the bifurcation. The ipsilateral leg22 is about 12 mm in diameter and continues along a length about 80 mmfrom the bifurcation 26 to a flared distal end or cuff 32 about 16 to 18mm in diameter when unconstrained. A contralateral stump 24 coextendsalong the ipsilateral leg and also has a diameter of about 12 mm with alength of about 35 mm. Preferably, the length of the contralateral stump24 is spaced from the ipsilateral leg 22 (gap 36) to easily be fittedover and seated against the bifurcation of the vessel at the iliacarteries, when the main stent graft body is pulled distally afterpartial deployment, that is, wherein the contralateral stump exits thedelivery sheath (see FIG. 6) and is deflected laterally upon expansionof stents 40 that have also exited the sheath after the sheath has beenpartially withdrawn distally.

[0032] Attachment tube 14 should have a diameter of about 26 mm, 28 mmor 30 mm or greater when unconstrained, and could have one of severalselected lengths, with attachment stent 50 exposed about 15 mm or sobeyond the proximal end 46 of the stent graft material. Distal endportion 44 would be overlapped by the proximal end portion 30 of themain stent graft device 12 and would be at least about 20 mm in lengthwithin the proximal end portion 30. For most aneurysms, the attachmenttube length would be about 70 mm between proximal and distal ends 46,48, of which the overlap length would be at least 20 mm; for largeraneurysms the attachment tube length would be about 85 mm; and forsmaller aneurysms, the length of the attachment tube could be about 50mm. Whenever the longest possible overlap is desired with the main stentgraft device, the longest attachment tube should be utilized.

[0033] Attachment tube 14 may have optional modifications: (a) it mayhave side holes or U-shaped fenestrations to allow for overstenting ofthe lower renal artery, accessory renal arteries as well as mesentaricvessels, or even both renal arteries in short necks; (b) it may havelarger gaps between stents for better adaptation for tortuous orshrinking necks, or both. In these instances, there is a need for atwo-step trigger mechanism that keeps the tube restrained to a smallerdiameter than the lumen dimension in order to make corrections to itsposition both rotationally or longitudinally.

[0034] Contralateral tube or leg 16 is associated with contralateralstump 24 and would be similar in size and shape to ipsilateral leg 22,having a primary diameter of about 12 mm, an overlap length of about 35mm, a length to a flared distal end of about 50 mm, and a flared end ofabout 18 to 20 mm in diameter when unconstrained.

[0035] Intragraft tube 18 would be similar to attachment tube 14 butwithout an attachment stent like stent 50. Thus, it would have adiameter when unconstrained of about 26 to 30 mm, and would have a totallength of about 50 to 80 mm. Intragraft tube 18 is shown deployed inFIG. 10.

[0036] Now, with reference to FIGS. 5 to 7, general deployment of thestent graft assembly of the present invention will now be described.Delivery of the stent graft assembly to the site of the abdominal aorticaneurysm (AAA) 70 comprises the following steps:

[0037] 1) position and partially deploy from the first delivery system100, the main stent graft tube 12 within the aneurysm 70, until thecontralateral stump 24 is released from the sheath 102, while retainingthe ipsilateral iliac limb 22 within the sheath of first delivery system100 to maintain control (FIG. 5);

[0038] 2) insert guide wire 122 into the contralateral stump 24 from thecontralateral iliac artery 76, and pull the main stent graft 12 towardthe bifurcation 72 of the aorta 74 within the aneurysm 70, for thecrotch of bifurcation 26 of main stent graft body 12 to become seated onthe bifurcation 72 (as in FIGS. 6 and 7) and for contralateral stump 24to extend along contralateral iliac artery 76 while ipsilateral leg 22extends along ipsilateral iliac artery 78;

[0039] 3) determine the location of renal arteries 80, 82 with respectto the vessel's bifurcation 72 and the proximal end 28 of the main stentgraft body 12, and select the appropriate length of attachment tube 14to be delivered to the main stent graft body for attachment at theproximal end thereof;

[0040] 4) endovascularly introduce the second delivery system 120 by wayof the contralateral iliac artery 76 along second guide wire 122,

[0041] 5) deploy the attachment tube 14 at the renal arteries, as seenin FIG. 7, by first releasing distal end portion 44 from a first sheath124 of delivery system 120 within proximal end portion 30 of main stentgraft body 12 and then releasing attachment stent 50 from introducer ordilator 128, and inflating the balloon 170 (see FIG. 13) for modelingthe attachment tube for expansion and vessel wall attachment byattachment stent 50;

[0042] 6) deploy the contralateral leg 16 from within a second sheath174 (see FIG. 13) of second delivery system 120 so that its proximal endexpands within contralateral stump 24 (FIG. 7), then fully release cuff58 into contralateral iliac artery 76;

[0043] 7) fully deploy ipsilateral leg 22 within ipsilateral iliacartery 78 by withdrawing the sheath 102 of first delivery system 100,thus completing stent graft assembly 10; and

[0044] 8) remove the delivery systems 100 and 120 for completion of theangioplasty.

[0045]FIGS. 8 and 9 generally depict forces upon a stent graft within ananeurysm 70 from blood flow after installation of a stent graft, withFIG. 8 illustrating the response of a conventional stent graft 90 whileFIG. 9 illustrates the response of the stent graft 10 of the presentinvention. A stent graft deployed within an aneurysm most commonly isconstrained to assume an arcuate shape. Blood flow from the proximalaneurysm entrance at the renal arteries toward the iliac arteries(indicated by the solid arrow) results not only in pressure on thebifurcation 36 but also pressure on the convex side of the stent graftwall, tending to urge the convex side wall further in the convexdirection as represented by the small arrows, and this results inpulling by the stent graft wall on the proximal and distal ends of thestent graft sufficiently stressing the stent graft-vessel wallattachments of the prior art stent graft 90 (also represented by smallarrows) for at least one of the two ends to move toward the aneurysm.With the stent graft 10 of the present invention, the frictionalengagement between the attachment tube and the main stent graft body 12in the overlapping region 64 permits incremental movement in response tothe stress such that neither the proximal nor distal ends of the stentgraft become dislodged, nor is the stent graft explanted.

[0046] Intragraft tube 18 could be later deployed by a delivery systemto underlie and support the overlapping region, so that it is positionedpartially within both the main stent graft tube 12 and the attachmenttube 14 as seen in FIG. 9. FIG. 10 depicts lengthening of an aneurysmsite after installation of a stent graft, as the aneurysm 70 (inphantom) gradually shrinks to smaller sizes such as indicated by 70′ andallowing the aorta walls eventually to generally assume their originalpre-aneurysm length. Stent graft assembly 10 of the present invention isresponsive to such lengthening by permitting incremental movement of theattachment tube 14 with respect to the main stent graft 12 at theoverlapping region 64. Shown in FIG. 10 is intragraft tube 18 disposedwithin stent graft assembly 10 underlying and extending beyond theoverlapping region 64 of the attachment tube 14 and main stent graft 12,with proximal end 66 and distal end 68 of intragraft tube 18 shown inphantom to be located beyond the ends of overlapping region 64.Intragraft tube 18 thus supports stent graft 10 spanning the overlappingregion, and its self-expanding stents provide an expansive forceoutwardly such that the outer surface of tube 18 presses outwardlyagainst and frictionally engages the interior surfaces of bothattachment tube 14 and main stent graft 12 in a manner permittingincremental movement therebetween while assuring the continuity andintegrity of the stent graft.

[0047] Referring to FIGS. 11 to 13, the delivery system 120 for theattachment tube 14 (and contralateral limb 16) will now be described,having a first (or outer) sheath 124, a top cap 126 and tapered dilator128 at proximal end 130, and a fitting 132 at distal end 134 of thedelivery system. Top cap 126 is affixed to the distal end of dilator128, which is affixed at the proximal end of a small diameter innercannula 136 that extends completely through the delivery system to adistal end. Fitting 132 is affixed to first sheath 124, and joined tothe side of fitting 132 is injection system 138, for saturating thestent graft with anticoagulant heparin prior to deployment, andoptionally for the injection of contrast medium thereafter. At thedistal end of fitting 132 is a check-flow valve 140 through whichextends pusher 142. Distally of pusher 142 is seen handle 144 of innercannula 136, and trigger wire control systems 146.

[0048] Stylet 148 extends through inner cannula 136, through pusher 142and first sheath 124 and top cap 126 to a proximal tip 150 thatprotrudes from the proximal end of the tapered dilator 128; stylet 148is of protective value during shipping and handling but is removed priorto use in the medical procedure. Tabs 152 are provided at the distal endof short sheath 154, for peeling away the sheath prior to the medicalprocedure; sheath 154 protects the patency of the introducer lumen atthe check-flow valve during shipping and handling, and extends only intofitting 132. For protection of the distal end components duringhandling, a protective tube 156 is secured therearound, and it also isremoved prior to the procedure.

[0049] Trigger wire control systems 146 are shown in greater detail inFIG. 12. Control systems 146 for the two trigger wires 158, 160 of thedelivery system 120 each include a safety lock 162 that is removedlaterally, and a release ring 164 that is moved distally (away from thepatient) parallel to the inner cannula 136 and pulls the respectivetrigger wire out of the assembly. The trigger wire 158 for securing theattachment stent 50 of the attachment tube 14 against any axial movementuntil released, is first to be removed prior to being able to actuatethe controls for trigger wire 160 that secures the distal end portion 44of the attachment tube against any axial movement until released. Also,the release ring 164 for the distal end portion may be a different colorthan that for the attachment stent, to clearly indicate to the physicianwhich trigger wire the particular control system actuates. The releaserings 164 have axial slots 166 therealong to permit lateral removal fromabout the inner cannula 136. Pin vise 168 tightens upon and releasesinner cannula 136 so that top cap 126 and dilator 128 can be advanced todeploy and be withdrawn for docking and system withdrawal.

[0050] Referring now to FIGS. 13 and 14, both the attachment tube 14 andthe contralateral leg 16 would be loaded in second double sheathdelivery system 120. In one arrangement, the second double sheathdelivery system would include an inflation balloon 170 adjacent to thedilator, followed by the attachment tube 14 in the first or outer sheath124, and the pusher for the attachment tube and the contralateral leg 16and its pusher 172 all in the second or inner sheath 174. In a secondarrangement shown in FIG. 14 having a smaller size, the attachment tube14 would be adjacent the distal tip in the first sheath 124, and theballoon 170, the attachment tube pusher and the contralateral leg 16 andits pusher 172 would be in the second sheath 174.

[0051] Deployment of the main stent tube body 12 and attachment tube 14is more particularly shown in FIGS. 15 to 18. In FIG. 15, main stentgraft body 12 has been partially deployed, with ipsilateral leg 22 stillretained within sheath 102 of delivery system 100. Proximal end portion30 has been released and has self-expanded. Second delivery system 120has been inserted through contralateral stump 24 with dilator 128extending beyond proximal end 28 along second guide wire 122.

[0052] Referring to FIG. 16, attachment tube 14 is seen being partiallydeployed from first sheath 124, with attachment stent 50 stillrestrained within the distal end of top cap 126 of dilator 128, and withproximal end 46 held closed by the top cap while the stent within theproximal end portion 42 is further held closed by trigger wire 158 andsuturing 176. In FIG. 17, the distal end portion 44 of the attachmenttube has been pushed from first sheath 124 and has deployed within theproximal end portion 30 of main stent body 12, while attachment stent 50remains restrained by dilator 128. FIG. 16 illustrates the ends 54 ofstruts 52 of attachment stent 50, after they have self-expanded uponrelease from top cap 126. Barbs 178 are affixed to struts 52 and willattach to vessel walls of the aorta upon full self-expansion.

[0053] Prior to deployment, the proximal end of the attachment stent 50may be held closed by top cap 126 of the dilator, as shown in FIGS. 16and 17, which is withdrawn from the attachment tube when properlypositioned, as is conventionally used with some stent grafts; or aspreferred, it may be held closed by trigger wire and sutures, asdisclosed in WO 98/53761, actuatable from controls at the distal endexternal to the patient. With reference to FIGS. 19 and 20, trigger wire158 is disposed within a small-diameter inner cannula 136 extendingthrough the delivery system and includes a proximal release end 180within the top cap 126, that initially extends through a loop at the end54 of one of the pairs of joined struts 52 of the attachment stent 50,holding the stent loop against the small-diameter cannula. A suture 176extends from the trigger wire release end 180 to two or more of theother loops of the attachment stent to initially maintain the proximalend of the stent 50 gathered in a closed position. Upon actuation of thetrigger wire controls (FIG. 12), the wire is withdrawn from the stentloop and the suture 176 allowing the stent proximal end to self-expand.A similar trigger wire system preferably is used to secure the stent atthe distal end portion 44. Such a system may also be used with deliverysystem 100 to deploy at least the proximal end portion 30 of the mainstent graft body.

[0054] In FIGS. 18 to 20, the trigger wire 158 is shown in detail inrelationship to attachment stent 50 of attachment tube 14. FIG. 19illustrates attachment stent 50 before top cap 126 has been placed overthe exposed struts 52, during which a suture holds the strut ends 54gathered near the inner cannula; the suture is removed once the top capis in place. Trigger wire 158 extends from its control section 146 alonginner cannula 136 of the delivery system 120 within pusher 142, andincludes a release end 180 that extends outwardly through an aperture ofproximal pusher body 182 and forwardly through attachment tube 14 andthen outwardly thereof near proximal end 42 thereof, then forwardly andinto a small aperture of the top cap and through a loop at the joinedproximal ends 54 of a pair of struts 52 and then further into thedilator, held therein by friction fit by the inner cannula threaded intothe dilator. Release end 180 of trigger wire 158 holds the exposedstruts of the attachment stent within the top cap, fixed against axialmovement with respect to the top cap and dilator. Top cap 126 surroundsall the exposed struts 52 of attachment stent 50 when the attachmenttube 14 is delivered to the site of the ruptured aneurysm, until it isaccurately positioned at the aneurysm neck.

[0055] First sheath 124 is then pulled distally with respect toattachment tube 14 by manual movement of fitting 132 while the struts ofthe attachment stent are held within and still restrained within top cap126, as seen in FIGS. 18 and 20, after which trigger wire 158 is pulledfrom the top cap and withdrawn completely from the catheter, thusreleasing the loop of the attachment stent struts. With the attachmenttube held against axial movement relative to pusher 142 by trigger wire160, the dilator/topcap/cannula subassembly is pushed forwardly(proximally) by pushing forwardly on cannula handle 144 to release theattachment stent 50, whereupon the ends 54 of struts 52 self-expandradially outwardly to engage the vessel wall, and barbs 178 seat intothe vessel wall to thereafter secure the attachment tube 14 in itsdesired position. Such a trigger wire system is disclosed in WO98/53761. Optionally, a molding balloon may be used to inflate withinself-expanded attachment stent 50 to assuredly press the struts againstthe vessel wall and seat the barbs.

[0056] Similarly, as shown in FIG. 20, the second trigger wire 160secures the distal end portion 44 of attachment tube 14 against anyaxial movement as the top cap 126 is being urged forwardly fromattachment stent 50 which would tend to pull the attachment stent andthe main body due to friction. Trigger wire 160 includes a release end184 that first extends outwardly from proximal pusher body 182 and alonggroove 186, then inwardly through the graft material of the distal endportion 44 and through a stent end loop and into an opening in theproximal pusher body, and then forwardly along inner cannula 136 whereit is held in a force fit thereagainst by the proximal tip of pusher142. Then, upon actuation of the control system 146 for trigger wire160, trigger wire 160 is pulled from the delivery system which releasesthe distal end portion 44 of the attachment tube 14 which then fullyself-expands within the aneurysm toward the vessel wall.

[0057] Proximal pusher body 182 is then pushed proximally throughnow-deployed attachment tube 14 to abut against the distal end of thetop cap 126; the abutment portion of proximal pusher body 182 has anouter diameter the same as the distal end of the top cap. Theconfiguration of proximal pusher body 182 is shown in FIG. 20. Uponpulling the dilator/topcap/cannula subassembly distally, and in turnupon moving proximal pusher body 182 distally, tapered surfaces of thedistal end (not shown) of the proximal pusher body gently engage anddeflect radially outwardly any portions of the stents of the main bodyto prevent any stubbing or snagging that otherwise would occur byengagement of the top cap distal end were it to be exposed when pulleddistally through the now-deployed attachment tube 14. Proximal pusherbody 182 similarly has tapered surfaces 188 at its proximal end thatgently engage and deflect outwardly any stent portions when it is pushedproximally through the main body to abut top cap 126.

[0058] As an option, the contralateral stump 24 of the main stent graftbody 12 may be sutured to an initially closed position so that the mainstent graft body may easily be pulled against the bifurcation 26. Asshown in FIG. 21, the suture 190 extends through the loops of the stent40 disposed along the outer surface of the contralateral stump's distalend 34, and is released after positioning by actuation of anothertrigger wire 192.

[0059] With the present invention are the following attendantadvantages:

[0060] 1) it has a modular concept for optimal on-site adaptation to aparticular aneurysm site;

[0061] 2) the use of an attachment tube with the main stent graft fillsthe entire length of the abdominal aortic aneurysm and gives the stentgraft more stability;

[0062] 3) the attachment tube enables the largest possible overlappingcoextension, which increases stability and gives more safety by way ofthe resultant double wall, even in case of fabric tear;

[0063] 4) the overlapping coextension at the same time allows freedomfor the stent graft to adjust: the top of the graft assembly will not bepulled down by blood flow after placement, and the bottom part will bepushed down against the aortic bifurcation; and

[0064] 5) the intragraft tube further assures the integrity of the stentgraft and its ability to adjust incrementally as the aneurysm changeslength.

[0065] The new concept was developed upon observation of the largest andclosest follow up of first and second generation stent grafts. It is thefirst time that a graft design is modified extensively according toclinical experience with graft configuration changes and resultingcomplications. At the same time the new concept allows the advantage ofextensively clinically tested components like stainless steel or nitinolstents, Dacron weave, and conformity. The new concept uses provencomponents in a modified manner that is based on the most extensivedocumentation and clinical analysis and most profound understanding oflate graft behavior and changes in man.

[0066] With present-day systems, the increased precision and improvedlong term safety is at the price of a larger introducer system at thecontralateral site, requiring surface dissection. With the long taperednose cone-tip of the present invention, the contralateral artery can bepunctured for insertion of the second double-sheath delivery system andthe artery needs less dissection, just for clamping during directsuture. Attempts can be made to reduce the introducer sheath by totalremoval or repositioning the dilatation balloon, which confines packingspace.

[0067] Weave and stent material may be thinner. The new concept ofoverlapping tubes allows probably the attachment and inner one to beless rigid and thinner. Weave probably can be made thinner and moreporous per the inner tube at least, in the future. A newweave-generation could be tested thereby clinically in this positionwithout the use of silk. Tears can easily be repaired by placement of asecond tube later.

What is claimed is:
 1. An endovascular stent graft comprising: a mainstent graft body having at least one stent secured to graft material,the stent graft body having a main body section defining a lumenextending from a proximal end to a bifurcation, and further having anipsilateral leg portion and a contralateral portion extending integrallyfrom the main body section at the bifurcation to respective distal endsand defining respective lumens; and an attachment graft tube havingproximal and distal end portions and defining a lumen therethrough andfurther including an attachment stent extending from the proximal endportion, wherein the attachment graft tube is securable to the mainstent graft body at an overlapping region, the attachment graft tubedistal end portion being securable to and within the proximal endportion of the main stent graft body at the overlapping region, upondeployment.
 2. The stent graft of claim 1 wherein the attachment grafttube is securable to the main stent graft body by a friction fitgenerated by spring forces of a self-expanding stent within theattachment graft tube distal portion pressing radially outwardly againstthe expanded proximal end portion of the main stent graft body, upondeployment.
 3. The stent graft of claim 1 further comprising anintragraft tube having proximal and distal end portions, wherein theintragraft tube is disposed to extend from within the lumen of the mainstent graft body proximally into the lumen of the attachment graft tube,and the intragraft tube underlying, supporting and extending beyond theoverlapping region, upon deployment.
 4. The stent graft of claim 3wherein the intragraft tube is securable to both the main stent graftbody and the attachment graft tube by a friction fit generated by springforces of a plurality of self-expanding stents, respective ones of whichare within at least the intragraft tube distal and proximal portions,pressing radially outwardly against the expanded proximal end portion ofthe main stent graft body and the expanded distal end portion of theattachment graft tube, upon deployment.
 5. The stent graft of claim 1further comprising a contralateral leg extension for being secured tothe distal end of the contralateral portion.
 6. An endovascular stentgraft comprising: a main stent graft body having at least one stentsecured to graft material, the stent graft body having a main bodysection defining a lumen extending from a proximal end to a bifurcation,and further having an ipsilateral leg portion and a contralateralportion extending integrally from the main body section at thebifurcation to respective distal ends and defining respective lumens; acontralateral leg extension for being secured to the distal end of thecontralateral portion; an attachment graft tube having proximal anddistal end portions and defining a lumen therethrough and furtherincluding an attachment stent extending proximally from the proximal endportion, wherein the attachment graft tube is securable to the mainstent graft body at an overlapping region, the attachment graft tubedistal end portion being securable to and within the proximal endportion of the main stent graft body at the overlapping region by afriction fit generated by spring forces of a self-expanding stent withinthe attachment graft tube distal portion pressing radially outwardlyagainst the expanded proximal end portion of the main stent graft bodyupon deployment; and an intragraft tube having proximal and distal endportions, wherein the intragraft tube is disposed within the lumenextending from the main body section of the main stent graft proximallyinto the lumen of the attachment graft tube, and the intragraft tubeunderlying, supporting and extending beyond the overlapping region, theintragraft tube being securable to both the main stent graft body andthe attachment graft tube by a friction fit generated by spring forcesof a plurality of self-expanding stents, respective ones of which arewithin at least the intragraft tube distal and proximal portions,pressing radially outwardly against the expanded proximal end portion ofthe main stent graft body and the expanded distal end portion of theattachment graft tube, upon deployment thereof.
 7. An endovascular stentgraft for treatment of an aneurysm in a vessel having a bifurcationcomprising: at least main stent graft body having at least one stentsecured to graft material the stent graft body having a main bodysection defining a lumen extending from a proximal end to a bifurcation,and further having an ipsilateral leg portion and a contralateralportion extending integrally from the main body section at thebifurcation to respective distal ends and defining respective lumens;and the main body section having a length extending from the bifurcationto the proximal end that is less than the span of the aneurysm.
 8. Thestent graft of claim 7 wherein the proximal end of the main stent graftbody is free of any vessel attachment mechanism.
 9. A first stent graftmember to be used in conjunction with at least one other stent graftmember to form a stent graft assembly to be located within a vessel of apatient, the first member comprising at a proximal portion thereof afirst attachment region for enabling the first member to be attached viaat least one stent to a proximal part of the vessel, wherein the firstmember further comprises at an outer surface of a distal portion thereofa second attachment region extending over the outer surface and servingto provide a region in which the other stent graft member can beattached to the first member, and wherein the distal part of the firstmember is to extend significantly within at least the proximal portionof the other member.
 10. A first stent graft member according to claim 9, further comprising an additional graft tube to be attached to asection of the first member and designed to extend in a distal directionwithin the other member.
 11. The method of placing an endovascular stentgraft in a vessel at a bifurcation thereof where branch vessels join thevessel, for treating an aneurysm thereat, comprising the steps of:placing a bifurcated main stent graft body in the aneurysm unattached toa wall of the vessel with a first leg portion in a first branch vessel;urging a bifurcation of the main stent graft body into a seated positionagainst the bifurcation of the vessel to move a second leg portion in asecond branch vessel; and deploying an attachment mechanism of the stentgraft to attach to walls of the vessel beyond the aneurysm.
 12. Themethod as set forth in claim 11 , wherein the attachment mechanism isaffixed to a proximal end portion of an attachment graft tube, and thestep of deploying includes delivering the attachment graft tube to aproximal end of the main stent graft body and securing a distal endportion of the attachment graft tube to the proximal end of the mainstent graft body.
 13. The method as set forth in claim 12 furtherincluding the step of delivering an intragraft tube into the proximalend portion of the main stent graft body and the distal end portion ofthe attachment graft tube, and securing the intraluminal graft tube toboth the main stent graft body and attachment graft tube.
 14. A methodof placing an endovascular stent graft in a vessel at a bifurcationthereof where branch vessels join the vessel, for treating an aneurysmthereat, comprising the steps of: placing a bifurcated main stent graftbody in the aneurysm unattached to a wall of the vessel with a first legportion in a first branch vessel; urging a bifurcation of the main stentgraft body into a seated position against the bifurcation of the vesselto move a second leg portion in a second branch vessel; and securing thestent graft to the vessel wall.
 15. A delivery system for endovasculardevices, comprising: a first sheath having a distal end and a proximalend and containing at least a first expandable device at a proximal end;a second sheath movable within the first sheath and having a respectivedistal end and a respective proximal end, the respective proximal endconcluding distally of the first expandable device and containing asecond expandable device; a first pusher associated with the firstexpandable device extending thereto within the first and second sheathesfrom a first proximal control pusher end exposed at the distal ends ofthe first and second sheathes; and a second pusher associated with thesecond expandable device extending thereto within the first and secondsheathes from a second distal control pusher end exposed at the distalends of the first and second sheathes.